The Guildline 9210 is a multivalue metrology current shunt, but can also be used as a low ohm standard resistor. The nominal output voltage 100 mV matches the lowest range of the 3458A.
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The box contains 6 precision shunts which all share the same voltage terminals P1 and P2. That is clever because tampering the voltage connections during the measurements or calibrations is a remarkable source of error. The Guildline style construction allows to connect the voltage wires beforehand and let them thermally stabilize. For the current connections (where the thermal EMF doesn't matter) there is a common terminal C1 and six C2 terminals, one for each current range.
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The resistive material is Zeranin which is a later developed improved version of Manganin.
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Each shunt is made of multiple parallel Zeranin wires connected between the (black painted) copper bars. The highest range shunt contains 25 parallel wire sections.
This stress free construction allows free thermal expansion and much reduces the hysteresis compared with the traditional sheet metal shunts.
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Built in a Formica case like most Guildline instruments. Ventilation grills on both sides makes it easy to add forced air cooling.
The holes are large enough for thermistor leads. Glueing small glass thermistors to the highest range shunts allows to accurately measure and compensate the temperature coefficient.
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These Guildline shunts seem to be rare in the used market. I have spotted a few in calibration labs, but never seen one in Ebay. This specific unit came from a closed military lab.
The German test equipment dealer Helmut Singer has one. I know that Guildline stuff can be expensive, even second hand. But 3867,50 euros. Seriously Helmut?
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